Zhang Yiqiang, Zahir Zahir A, Frankenberger William T
Department of Environmental Sciences, University of California, Riverside, CA 92521, USA.
J Environ Qual. 2004 Mar-Apr;33(2):559-64. doi: 10.2134/jeq2004.5590.
Bacterial reduction of selenate [Se(VI)] to elemental Se [Se(0)] is considered an effective bioremediation technique to remove selenium (Se) from agricultural drainage water. However, the fate of the newly formed Se(0) in aquatic systems is not known when it flows out of the treatment system. A set of laboratory experiments was conducted to determine the fate of the colloidal-particulate Se(0) in a water column and in a water-sediment system. Results showed that the newly formed colloidal-particulate Se(0) followed two removal pathways in aquatic systems: (i) flocculation-sedimentation to the bottom of the water and (ii) oxidation to selenite [Se(IV)] and Se(VI). During 58 d of the experiments, 51% of the added Se(0) was precipitated to the bottom of the water and 47% was oxidized to Se(IV) in the water column. In the water-sediment system, Se(IV) in the water accounted for 21 to 25% of the added Se(0). Adsorption of Se(IV) to the bottom sediment resulted in a relatively low amount of Se(IV) in the water. This study indicates that the newly formed Se(0) may be an available form of Se for uptake by organisms if it flows to aquatic systems from a treatment site. Therefore, an effective bioremediation system for removing Se from drainage water must reduce Se(VI) to Se(0) and remove Se(0) directly from the drainage water.
将硒酸盐[Se(VI)]细菌还原为元素硒[Se(0)]被认为是一种从农业排水中去除硒(Se)的有效生物修复技术。然而，当新形成的Se(0)流出处理系统时，其在水生系统中的归宿尚不清楚。进行了一组实验室实验，以确定胶体颗粒态Se(0)在水柱和水-沉积物系统中的归宿。结果表明，新形成的胶体颗粒态Se(0)在水生系统中遵循两条去除途径：(i)絮凝沉淀至水底；(ii)氧化为亚硒酸盐[Se(IV)]和硒酸盐[Se(VI)]。在58天的实验期间，51%添加的Se(0)沉淀至水底，47%在水柱中氧化为Se(IV)。在水-沉积物系统中，水中的Se(IV)占添加Se(0)的21%至25%。Se(IV)吸附到底部沉积物导致水中Se(IV)的量相对较低。本研究表明，如果新形成的Se(0)从处理场地流入水生系统，它可能是生物体可利用的硒形态。因此，一种有效的从排水中去除硒的生物修复系统必须将Se(VI)还原为Se(0)并直接从排水中去除Se(0)。
